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选取广西环江县喀斯特峰丛洼地:草丛(T)、灌丛(S)、原生林(PF)(中坡位)不同植被类型,原生林上、中、下不同坡位,按土壤发生层采集淋溶层(A层,0—10 cm)、过渡层(AB层,20—30 cm,草丛和灌丛;30—50 cm,原生林)、淀积层(B层,70—100cm)样品,研究土壤微生物量碳、氮(Soil microbial biomass carbon(SMBC)、soil microbial biomass nitrogen(SMBN))、微生物碳熵、氮熵(ratio of SMBC to soil organic carbon(qMBC)、ratio of SMBN to soil total nitrogen(qMBN))、土壤基础呼吸(soil basicrespiration(SBR))以及代谢熵(microbial metabolic quotient(qCO2))的剖面分异特征及其影响因素。结果表明,植被、土层深度显著影响土壤微生物量及基础呼吸,随植被恢复,SMBC、SMBN、SBR由草丛、灌丛、原生林依次上升,并随土壤发生层位的加深逐渐减少,qCO2在3种植被类型间差异显著:T>PF>S;原生林A层SMBC,SMBN在各坡位间均显著高于AB层、B层,SBR在A层由下坡位至上坡位递减,而在AB和B层的上、下坡位间无显著差异,qCO2坡位间无显著差异(P>0.05);SMBC与SMBN之间存在显著正相关(r=0.825,P<0.01,n=45),且SMBC、SMBN、SBR分别与有机碳、全氮、碱解氮均呈显著正相关。因此,随植被恢复,土壤质量明显改善,且坡位对A层土壤的影响较AB层和B层更显著,对于维持土壤微生物调节的土壤养分循环功能,调控土壤氮素营养与土壤有机质同等重要,这为合理制订喀斯特生态恢复措施提供了理论依据。
According to the different vegetation types of grassland (T), shrub (S), primary forest (PF) (mid-slope), and different slope positions of primary forest, middle and lower, The leaching layer (A layer, 0-10 cm), transition layer (AB layer, 20-30 cm, grass and shrubs; 30-50 cm, primary forest), sediment (B layer, 70-100 cm) (SMBC), soil microbial biomass nitrogen (SMBN), microbial carbon entropy, ratio of SMBC to soil organic carbon (qMBC), ratio of SMBN to soil total nitrogen (qMBN)), soil basicrespiration (SBR) and metabolic metabolic quotient (qCO2). The results showed that the depths of vegetation and soil affected soil microbial biomass and basic respiration significantly. With the restoration of vegetation, SMBC, SMBN and SBR increased gradually from grassland, shrub and virgin forest, and decreased with the deepening of soil layers. The SMBC and SMBN of A layer in primary forest were significantly higher than those in AB layer and B layer, respectively, and the SBR decreased from downhill to uphill in layer A There was no significant difference between upper and lower slopes of AB and B, there was no significant difference in qCO2 (P> 0.05); there was a significant positive correlation between SMBC and SMBN (r = 0.825, P <0.01, n = 45 ), And SMBC, SMBN, SBR were significantly and positively correlated with organic carbon, total nitrogen and available nitrogen. Therefore, with the restoration of vegetation, the quality of soil was obviously improved, and the effect of slope position on soil layer A was more significant than that in soil layer AB and layer B. Soil nutrient cycling and soil nitrogen regulation were as important as soil organic matter , Which provides a theoretical basis for the reasonable formulation of karst ecological restoration measures.